In order to thermally insulate or heat objects to be heated, such as various apparatuses, equipment, and piping connected thereto, the pipes have conventionally been surrounded with jacket heaters having flexibility. Also in the case of thermally insulating or heating curved surfaces, e.g., the lateral surfaces of apparatuses, the same jacket heaters are mounted. Incidentally, such jacket heaters are also called mantle heaters.
Known as such a jacket heater is the mantle heater 10 shown in FIG. 5. The present applicant proposed, in patent document 1, a mantle heater 10 having a multilayer configuration in which a heating element 300 made of an inorganic-fiber sheet 303 and a heating wire (not shown) attached thereto and a thermal insulator 400 are superposed with each other and placed between an inner-layer material 100 formed of a fluororesin sheet and an outer-layer material 200. The heating wire is an electric heater wire, and power lines 306 which extend to the outside of the inner-layer material 100 and outer-layer material 200 have been connected to the electric heater wire. A receptacle outlet 307 is connected to an external power source (not shown) to feed electric power. When this mantle heater 10 is mounted on a straight pipe 20, the two peripheral edge parts 103 and 104 extending in the longitudinal direction are put together in a butt arrangement and are connected to each other by means of a hook-and-loop fastener 105 and 106 disposed on the edge surfaces.
Such a mantle heater 10 has flexibility and generates little dust, and hence has advantages in, for example, that the heater can be used in clean rooms or the like.